Problem: $\dfrac{20}{100} + \dfrac{19}{10} = {?}$
Answer: The fractions must have the same denominator before you can add them. Rewrite $\dfrac{19}{10}$ as $\dfrac{190}{100}$ $\dfrac{20}{100} + \dfrac{190}{100} = {?}$ $ = \dfrac{210}{100}$